Who said "Beat one opponent freely and you can beat the world."?

Miyamoto Musashi (c. 1584–1645). Source: The Book of Five Rings, Earth (The Five Scrolls).

What is the original Japanese?

一人の敵に自由に勝時は、世界の人に皆勝所也. Translated from the original Japanese by Spartan Surfers.

Beat one opponent freely and you can beat the world.

Miyamoto Musashi, The Book of Five Rings, Earth (The Five Scrolls)

The source

"Beat one opponent freely and you can beat the world." Miyamoto Musashi said it in The Book of Five Rings, Earth (The Five Scrolls). Translated from the original Japanese by Spartan Surfers.

"一人の敵に自由に勝時は、世界の人に皆勝所也"

Original Japanese, The Book of Five Rings, Earth (The Five Scrolls). Japanese: Miyamoto Musashi (Kinkodo, 1909), NDL digital text.

Who said it

Miyamoto Musashi (c. 1584–1645). Undefeated swordsman who wrote The Book of Five Rings in a cave a few weeks before he died.

Questions

Who said "Beat one opponent freely and you can beat the world."?: Miyamoto Musashi (c. 1584–1645). Source: The Book of Five Rings, Earth (The Five Scrolls).
What is the original Japanese?: 一人の敵に自由に勝時は、世界の人に皆勝所也. Translated from the original Japanese by Spartan Surfers.